From previous posts, we have seen that there is a great deal happening within the aprons. Now, we need to make room for one last thing…

Proper right apron interior showing upper & lower racks with spring mechanism.

In this post, I described the process fitting the stop rods keeping the top from shooting off the back of the carcass when the works are set into motion. Something similar is needed to keep the main box from coming out the front. Two (fairly) sizable bolts, to minimize the force exerted on the stops, were used in the original. These need to be installed from within the side compartments of the main box such that:

• they avoid contacting the lower racks,
• the grooves in which they run must not protrude through the carcass front,
• the main box is allowed to move to its fullest extent,
• they avoid interfering with existing guides and drives located on the main box sides, and
• they are installed above the main box floor.

Not too much to ask for, right?

Proper right compartment in the original main box. Circle shows stop bolt head (barely visible).

When Oeben created the original, he grooved the aprons just below the lower guides for the main box. This out-of-the-way location prevented anything else from interfering, allowing the bolts to slide unimpeded. So long as the bolts are installed behind the front legs, these channels won’t show through the carcass front. The other ends, naturally, aren’t a problem since the main box stops behind the rear apron.

Layout showing vertical alignment of main box and carcass.

This addresses the majority of the above criteria except for the “horizontal location”, or how far above the main box bottom are the bolts mounted? The challenge here lies in the limited available space between the lower racks, and the main box floor; less than 1/4 inch. Not much! Referring, once again, to the original, Oeben solved this by drilling a hole through the lower racks for the stop bolts to protrude. This has the added advantage of strengthening the bolts since overtime repeated collisions might loosen the bolts mounted in the wood alone.

Main box proper left side showing proposed stop bolt location.

As with the stop rods previously once these bolts are installed, they will be used to mark the location and extents of their grooves, and stop plates.

Postscript: having trouble visualizing things? Check out the first image in this post.